Fluid operated torque tool

Abstract: A fluid-operated torque tool for tightening and loosening threaded connectors has an engaging element having an axis and two axial ends with at least one of the ends adapted to engage a threaded connector to be tightened or loosened, and a driving element which is displaceable under the action of a working fluid in an axial direction of the engaging element and engages with the engaging element so that during the axial displacement of the driving element the engaging element turns about the axis and therefore tightens or loosens a threaded connector engaged by the engaging element.

Description: The present invention relates to a fluid-operated torque tool for tightening and loosening threaded connectors such as bolts, nuts and the like. Fluid-operated torque tools of the above mentioned general type are known in the art and are widely utilized. In known fluid-operated torque tools the tool works substantially perpendicular to the drive axis. In other words, when a fluid-operated torque tool has an engaging element which engages a threaded connector, and a drive formed as a fluid-operated cylinder-piston unit, the piston of the drive is displaced in an axial direction of the cylinder-piston unit, while the engaging element of the tool turns about an axis which is perpendicular to the axial direction of the cylinder-piston unit. Tools of this known type can be improved. Document FR-A-2 343 934 discloses a tool in which a driving shaft is turned in one direction when fluid power is applied to one side of a piston and remains stationary due to the provision of a ratchet mechanism when fluid power is applied to the other side of the piston. Thus the driving shaft is not turned in one and the same direction when the fluid power is applied to opposite sides of the piston. Document DE-C-949 999 discloses a tool in which the shaft is turned in one direction when fluid power is applied at one side of the piston and in the opposite direction when the fluid power is applied to the opposite side of the piston. In this known tool the driving shaft also is not turned in one and the same direction when the fluid power is applied to opposite sides of the piston. Document US-A-4 513 644 discloses a tool that turns a driving shaft in one direction when fluid power is applied to one side of a piston and turns the housing (38) of the tool in the opposite direction when fluid power is applied to the other side of the piston, while the drive shaft remains stationary. Also, the tool does not turn the driving shaft in one and the same direction when fluid power is applied alternately to opposite sides of the piston. Finally, the document FR-A-2 418 061 discloses a tool that has two driving motors, one rotary and one linear. The rotary driving motor turns the shaft until a certain torque has been reached, at which point the linear motor applies pressure to a piston which turns the shaft in the same direction. The shaft does not, however, turn in one and the same direction when fluid power is applied alternately to opposite sides of the piston. With this invention it is assumed that after the certain torque has been reached by the rotary motor, it will take less than a full stroke of the piston to reach the desired torque to be applied to a nut or the like being tightened or loosened. It is an aim of the present invention to provide a fluid-operated torque tool which avoids the disadvantages of the prior art. According to the present invention there is provided a fluid-operated torque tool as claimed in the ensuing claim 1. A fluid-operated torque tool according to the invention can be made of a simple construction requiring few parts and being of relatively small diameter. At the same time the tool is extremely powerful since a piston area in the tool takes up little space yet is larger than if a single cylinder-piston type drive is used. The first and second sets of helical formations are both provided on the central portion of the engaging element and are inclined in opposite directions. Suitably the tool may be provided with stationary members each provided with a plurality of teeth engageable with counter-teeth of respective ones of said first and second ratchets, the first and second driving members being cooperable with, and at the same time axially movable relative to, the first and second ratchets. Thus upon engaging the teeth of one ratchet with the teeth of its associated stationary member, the driving means continues to move axially relative to the ratchet and relative to the engaging element under the action of the working fluid. The tool may also have means including interengaging splines for connecting the first and second driving members with the first and second ratchets, respectively, so that the driving means is axially displaceable relative to the first and second ratchets. Conveniently the working fluid supplying, means includes a fluid cylinder for admitting the working fluid and displacing the driving means axially relative to the engaging element in the two opposite directions of the reciprocating displacement. Embodiments of the invention will now be described by way of example only with reference to the following drawings in which: Figure 1 of the drawings is a view schematically showing a partial cross-section of a fluid-operated torque tool embodying the present invention; Figure 2 is a view showing an engaging element of the inventive tool; and Figure 3 is an exploded view showing a driving element and ratchets of the inventive tool. DESCRIPTION OF THE PREFERRED EMBODIMENTS A fluid-operated torque tool in accordance with the present invention has an engaging element generally designated 1. The engaging element 1 is formed as an elongate stepped cylindrical shaft which has two end portions 2 and 3 each adapted to engage a threaded connector to be tightened or loosened. For example, the end portions 2 and 3 may be formed as rectangular or hexagonal members engageable in rectangular or hexagonal openings of sockets to be connected to a threaded connector. The engaging element 1 further has two portions 4 and 5 of a greater diameter than the portions 2 and 3. Finally, it has a central cylindrical portion 6 located between the portions 4 and 5. The central portion 6 has two sections provided with helical formations 8 and 9 formed, for example as helical teeth, which are inclined in opposite directions. In other words, starting from a central line 7 of the portion 6, helical formations 8 are inclined from the bottom left toward the top right, while helical projections 9 are inclined from top left toward the bottom right. Bushings 10 and 11 having flanged outer ends are arranged on the portions 4 and 5 of the engaging element and are fixedly connected to the housing of the tool by, for example, screws 12. The engaging element 1 turns relative to the bushings 10 and 11. Retaining members 13 retain all parts of the tool together and are fixedly connected to the shaft, for example by pins 14. The retaining members 13 are turnable relative to the bushings 10 and 11 due to interposition of bearings 15 between them, formed for example by balls. The inner ends of the bushings are provided with a plurality of teeth 18 and 19 which are spaced from one another in a circumferential direction transversely to the axis A of the engaging element 1 and inclined in opposite directions. The tool further includes a driving element 20 having two driving members 21 and 22 which are connected with one another, for example through a bearing 23 formed by balls, so that they are jointly axially displaceable and at the same time can rotate relative to one another. The tool further has ring-shaped ratchets 24 and 25 which are arranged non-turnably relative to the driving members 21 and 22, respectively, and are spring biased in an axial direction toward the bushings 10 and 11 by springs 26 and 27. The ratchets 24 and 25 are provided with teeth 28 and 29 which are engageable with the teeth 18 and 19 of the bushings 10 and 11, respectively. The driving member 21 is connected with the ratchet 24 by interengaging formations, for example splines 30, so that it can axially displace relative to the ratchet 24 and therefore relative to the engaging element 1. The driving member 22 is likewise connected with the ratchet 25 by interengaging formations such as splines 31 so that it also can axially move relative to the ratchet 25 and therefore relative to the engaging element 1. The driving members 21 and 22 have radially inwardly extending projections 32 and 33 which are provided with helical formations formed, for example, as helical teeth. The helical formations of the projections 32 and 33 are inclined in opposite directions and formed in correspondence with the helical projections 8 and 9 of the engaging element 1 so as to engage the latter. The tool also has a housing which is identified generally by reference numeral 34. The housing has two housing portions 35 and 36 which are connected to one another, for example by means of a threaded connection 37. The housing has two chambers 38 and 39 which do not communicate with one another. Working fluid such as, for example, hydraulic fluid can be alternatingly admitted into and withdrawn from the chambers 38 and 39. The fluid-operated tool in accordance with the present invention operates in the following manner. When working fluid, for example hydraulic liquid, is admitted from a source (not shown) to the chamber 39 the driving member 22 is pushed upwardly in the drawings and pushes upwardly the driving member 21. Since the teeth 28 of the ratchet 24 engage with the teeth 18 of the bushing 10, the driving member 21 cannot turn and instead moves axially upwardly relative to the ratchet 24 and relative to the engaging element 1. Since the helical formations 32 of the driving member 21 engage with the helical formations 8 of the engaging element 1, the axial upward displacement of the driving member 21 causes turning of the engaging element 1 in a predetermined direction identified by the arrow in Figure 1. During this upward axial displacement, the driving member 22 can turn relative to the driving member 21 and just follows, by its helical formation 33, the helical formations 9 of the engaging element 1 while the teeth 29 of the ratchet 25 just slip over the teeth 19 of the bushing 11. When thereafter the fluid is withdrawn from the chamber 39 and admitted into the chamber 38, the driving members 21 and 22 move axially downwardly. Since the teeth 29 of the ratchet 25 engage with the teeth 19 of the bushing 11, the driving member 22 cannot rotate and displaces axially downwardly relative to the ratchet 25 and relative to the engaging element 1. Due to the engagement of the helical formations 33 of the driving member 22 with the helical formations 9 of the engaging element 1, the engaging element 1 is turned in the same direction, while the driving member 21 turns relative to the driving member 22 and the teeth 28 of the ratchet 24 slip over the teeth 18 of the bushing 10. Therefore a continuous turning of the shaft is provided. In this way a fastener can, for example, be tightened. In order to reverse the tool from tightening to loosening, the tool is turned over so that the upper end of the engaging element 1 is engaged with the fastener. The fluid-operated torque tool is further provided with a reaction member which is identified with reference numeral 40. The reaction member has inner splines 41 which engage with outer splines 42 provided on both end parts of the housing. The reaction member as known can abut against neighboring objects, for example a side of a flange, an adjacent nut, or a base of a housing of the application. The reaction member can be removed from one axial side of the housing and attached to the other axial end of the housing during respective operations. In the embodiment shown the housing is formed as a cylinder having fluid-receiving chambers. It is believed to be clear that the cylinder can be arranged separately from the tool on top of it and operated so that it can be switched from one side to another side. However, this would make the tool longer. When the fluid-operated torque tool is designed in accordance with the present invention it has a simple construction and requires very few parts. It also has a relatively small diameter and at the same time is extremely powerful since the piston area provided in this tool takes up little space, and is yet larger than in tools with cylinder-piston units. While the invention has been illustrated and described with reference to a particular embodiment, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the scope of the present invention as it is defined in the appended claims.

Claims: A fluid-operated torque tool for tightening and loosening threaded connectors, comprising a housing (34); an engaging element (1) mounted in the housing (34) for rotation about its axis while being axially retained, the engaging element having a central portion (6) with first and second sections located near one another in the axial direction and two opposite axial end portions (2,3) at least one of which is formed and arranged relative to the housing to engage a threaded connector to be tightened or loosened; driving means (20) mounted for axial displacement relative to the engaging element (1) and having a first driving member (21); displacing means for supplying working fluid consecutively to opposite sides of the driving means (20) to displace the driving means axially relative to the engaging element (1) consecutively in a first axial direction and then in the opposite second axial direction; first engaging means in the form of a first set of helical formations (8) on said first section of said central portion (6); second engaging means in the form of first projections (32) on said first driving member (21), the first and second engaging means cooperating with each other on movement of the driving means (20) in said first axial direction under the action of working fluid supplied by said displacing means to turn the engaging element (1) relative to the housing (34) in a first rotational sense; and ratchet means comprising a first ratchet (24) connected to the first driving member (21) and arranged to prevent its rotation relative to the housing in a second rotational sense opposite to said first rotational sense while being free to rotate in said first rotational sense; characterised in that the driving means (20) further comprises a second driving member (22), the first and second driving members (21,22) being mounted about the engaging element (1) and connected to each other so that they are jointly axially displaceable while being capable of rotation relative to each other, in that the ratchet means further comprises a second ratchet (25) connected to the second driving member (22) so as to be axially displaceable relative thereto while being coupled therewith for rotation, the second ratchet (25) being arranged so that it is prevented from rotation relative to the housing in said second rotational sense while being free to rotate in said first rotational sense, in that the tool further comprises third engaging means in the form of a second set of helical formations (9) on said second section of said central portion and fourth engaging means in the form of second projections (33) on said second driving member (22), and in that the helical formations of said first set are inclined in opposite directions to the helical formations of said second set, said third and fourth engaging means cooperating with each other on axial movement of the driving means (20), the said engaging means (8,9,32,33) and the said first and second ratchets being constructed and arranged such that if the driving means (20) is moved in the first axial direction, the first ratchet (24) and the first driving member (21) are prevented from rotating in said second rotational sense so that, due to the cooperation of the first and second engaging means (8,32), the engaging element (1) turns relative to the housing (34) in the first rotational sense and the second driving member (22) and the second ratchet (25) rotate relative to the engaging element and the housing in the first rotational sense, and such that if the driving means is moved in the second axial direction, the second ratchet (25) and the second driving member (22) are prevented from rotating in said second rotational sense so that, due to the cooperation of the third and fourth engaging means, the engaging element (1) turns relative to the housing (34) in the first rotational sense and the first driving member (21) and the first ratchet (24) rotate relative to the engaging element (1) and the housing (34) in the first rotational sense, the engaging element (1) thereby turning only in one circumferential direction thereby tightening or loosening a threaded connector engaged by the engaging element. A fluid torque tool according to claim 1, characterised in that the tool further has stationary members (10,11) each provided with a plurality of teeth (18, 19) engageable with counter-teeth (28, 29) of respective ones of said first and second ratchets (24,25), said first and second driving members (21,22) being cooperable with, and at the same time axially movable relative to, said first and second ratchets (24,25), respectively. A fluid-operated torque tool according to claim 1 or 2, characterised in that the tool further has means (30,31) including interengaging splines for connecting said first and second driving members (21,22) with said first and second ratchets (24,25), respectively, so that the driving means (20) is axially displaceable relative to said first and second ratchets (24,25). A fluid torque tool according to any one of the preceding claims, characterised in that said working fluid supplying means includes a fluid cylinder (38, 39) for admitting the working fluid and displacing said driving means (20) axially relative to said engaging element (1) in the two opposite directions of the reciprocating displacement.

Inventors: JUNKERS JOHN K, JUNKERS, JOHN K.
Applicants: JUNKERS JOHN K, JUNKERS, JOHN K.
Application year: 1994
Main classification: B25B21
IPC codes: B25B13, B25B21